Automatically operable slack adjuster for air brakes



July 21, 1953 B, DOREY 2,646,140

AUTOMATICALLY OPERABLE SLACK ADJUSTER FOR AIR BRAKES filed May 29, 1950 4 Sheets-Sheet l 4 sheets-sheet 2 .UN `m m* m mm W m .MN R. 0 E T. ww mm m i m ff W. NM. NE Sv um .WN WN uw wm. N ma mm N m s. mmm

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n l n July 21, 1953 G. B. DoREY AUTOMATICALLY OPERABLE SLACK ADJUSTER FOR AIR BRAKES Filed May 29, 1950 July 21,"1953 G, B, DOREY, 2,646,140

AUTOMATICALLY OPERABLE SLACK ADJUSTER FOR AIR BRAKES Filed May 29, 195o 4'sheets-Sheet5 l F/a s A G. B. DOREY July 21, 1953 AUTOMATICALLY OPERABLE sLAcK ADJusTER FOR A13 BRAKES Filed May 29, 195o v 4 Sheets-Sheet 4 oN .l NN wm .l

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INVENTOR.

. Patented July 21, 1953 AUTOMATICALLYQPERABLE SLACK ADJUSTER, FOR BRAKES George B. Dorey, Westmount,v Quebec, Canada, assignor to Continental Transport Appliances,

liebec, Canada, a corpora- Limited, Montreal, Q tion of Canada Application May 29, 1950, Serial No. 164,871

17 Claims. (Cl. 18S-202) My invention relates to an improved autoi matically operable slack adjuster for the air brake of railway vehicles and the like.

The objects of the invention among others are to provide an automatically operating slack adjuster for maintaining the brake cylinder piston travel within the limits of 7 to 9 inches as required by the regulations of the Association of American Railroads and the Interstate Commerce Commission; to provide a mechanism for automatically shortening the center rod extending between the dead and live levers wherein the motive rpower is in the form of resilient energy reacting against a stationary part of the Vcar structure and wherein the resilient energy is built up during the power applying movement of the brake piston and released when the movement of the piston extends beyond the prescribed limits; to provide an improved form of right angular drive between a rotary take up device on the center rod and an actuating lever moving in a plane substantially parallel with the plane of the live lever; and to provide a bevel gear connection between a horizontally swinging lever and a rotary device on the center connection whereby a multiplied extent of swinging movement of the rotary device is obtained in relation to the swing of the horizontally disposed lever.

' My invention further resides in details of conl struction concerned with the construction of the take up device and with the construction and operation of the compressible mechanism.

For further comprehension of my invention reference may be had to the accompanying drawings wherein:

Figure 1 is a plan view of the Vbrake lever system of railway car showing my improved slack adjuster applied thereto, said View showing the center sills of the car and the brake cylinder supporting bracket in dot and dash lines.

Figure 2 is a vertical elevational side view of the compressible mechanism indicating the same in relation to the brake cylinder and associated push rod.

Figure 3 is a plan View of the take up device illustrating the 'same on an enlarged scale.

Figure 4 is a vertical side elevational View of the take up mechanism shown in Fig. 3.

Figure 5 is a vertical sectional elevational view of the take up device as seen on a line 5--5 of Fig. 4.

Figure 6 is a vertical end view of the take up device as viewed from left to right of Fig.` 4.

Figure 7 is a vertical sectional view through Figure 8 is a vertical sectional view through the take up device as taken on a line 8 8 of Fig. 4.

Figure 9 is a detached elevational view showing on an enlarged scale the compressible operating mechanism as seen in released position.

Figure 10 is a view similar to Fig. 9 except that the mechanism is shown with the spring compressed and the parts .positioned at approximately 6% inches of piston travel.

Figure 11 is a View of the outer end of the compressible mechanism showing the locking pawl in releasing position as the piston enters into the zone'where adjustment of piston travel is indicated.

, Fig. l2 is a vertical sectional View taken on a line |2-t2 of Fig. 9 showing the mounting of the anchoring bracket for the compressible mechanism. Y

Figure 13 is a detached elevational view of the guiding and holding bar forming a part of the compressible mechanism.

Figure 14 is a detached plan view of the guiding and holding bar shown in Fig. 13.

Figure 15 is a plan view of the actuating lever.

Figure 16 is a vertical longitudinal side view of the actuating lever shown in Fig. 15. v

Figure 17 is plan View of the end supporting member incorporated in the take up mechanism.

Figure 18 is a vertical side elevational view of the end supporting member shown in Figl'?.

Figure 19 is a side elevational view of the take up pinion.

Figure 20 is an end elevational view of the take up pinion shown in Fig. 19.

Figure 21 is a side elevational view of the take lup sleeve.

t means of bolts I3 and operable by said cylinder the take'up device as taken on a line 1--1 of Fig. 4.

is a piston structure, the outer end of which is indicated at I4, which acts upon a push rod l5 to force the same outwardly and constitutes the power applying means.

The brake generally includes top rods I6 which lead tothe trucks (not shown) at the respective ends of the car for operating the brake shoes (not shown). The leverage system extending between the top rods and the push rod includes live and dead levers indicated at l1 and i3 respectively and said levers are connected through a center tie connection structure i9. The center connection in this embodiment of my invention includes a rod section 2G having a pair of jaws 2| pivotally connected to the dead lever i8 by means of pivot 22 and the end of the said rod opposite to the jaws is provided with an exteriorly screw threaded section 23. Co-operating with the threaded section 23 is va sleeve 24 having an interiorly screw threaded section 25 engaging with the section 23 whereby variation in the length of the connection is effected by rotation of the sleeve.

The sleeve 2li is rotatably mounted in a yoke structure built up rfrom a pair of complementary jaw pieces 26 which each include an elongated body portion 21 extending lengthwise of the center connecting structure and the pair are disposed in facing relation and united adjacent each end as indicated at 28 and 29 respectively. The respective pieces 28 when in meeting relation present at one end a circularly shaped bearing section 3@ in which the sleeve is rotatably mounted and adjacent said bearing there is provided a vertically disposed end wall section 3i which constitutes a thrust bearing for the sleeve as will hereinafter be pointed out. The body portion 21 of each jaw piece is extended beyond the live lever and the two pieces are maintained i'n spaced relation by integrally formed thimbles 32.

The portion of the sleeve 24 which extends within the bearing section 39 of the yoke is in the form of a circular hub section 33 and at the opposite ends of said section are integrally formed collars as indicated at 3Q and 35 respectively.

The respective collars 34 and 35 act as thrust members to engage with the yoke and prevent relative axial-movement between the yoke and sleeve. The outer collar 34 is formed of hexagon or other non-circular shape to admit of receiving a wrench and thereby permit of the manual operation of the sleeve and said collar bears against'the edge 3E of the bearing 30 of the yoke. The inner collar 35 which constitutes the main thrust bearing whereby the pulling strains of the center rod are transmitted from the sleeve to the live lever through the medium of the yoke bears on the vertically disposed end wall 3i of the yoke.

rIhe sleeve, beyond the collar 35, is provided with a tubular extension 3'! which is welded or otherwise secured to the interior surface of the sleeve proper and overlying said extension there are segmental sections 38 which intercalate with similar segmental sections 39 of a ratcheting element 49. The ratchet element iii is in the form of yan axially slidable member and includes a circular flange 4i and a collar i2 having the edge portion in the form of serrations 43 which have axially inclined surfaces lli and locking face-s 45. The serrations i3 are uniformly spaced around the circumference of the collar and engage with similar serrations formed on the bevel gear pin- -ion 56. The serrations on the respective members @il and 46 are normally maintained in close engaging relation by means of a. helical compression spring il interposed between the collar 35 of the sleeve and the flange il of the member 40.

The bevel gear pinion 46 includes bevel gear teeth 48 and forwardly beyond the toothed section there is provided a trunnion like portion 49 which is extended within the vertically disposed end wall 5i of the end supporting member 52.

The end supporting member 52 includes upper and lower horizontally extending walls as indicated at 53 and 54 respectively and these walls in combination with the end wall 5l form a jaw like member which embraces the live lever. The said horizontally extending walls 53 and 55% are apertured at 55 for the accommodation of lugs 56 which are formed integrally with the yoke members 26.

The bevel gear pinion 46 is maintained against axial movement between the end of the tubular section 3l and the end wall 5! of the end supporting member 52. The pinion gear 45 is further supported by means of walls 5l' which depend from the inner face of the jaw pieces `25. The edge portions of said depending walls 5l are of arcuate shape as indicated at 53 and thus form` seats for supporting the sleeve port-ion oi the bevel gear pinion.

The actuating mechanism ifor the bevel gear pinion 46 includes a horizontally swinging lever 59 which is mounted on the lug 55 of the upper jaw piece 25 to swing about the yaxis of pivot Sii which latter forms the pivotal connection between the center tie rod structure and the live lever il. The said lever 59 is actually positioned between the upper wall 53 of the end supporting member 52 and the inner face of the upper jaw piece '26 and is there formed with a beveled toothed sector 6I having a plurality of beveled teeth 62 meshing with the beveled teeth 48 of the pinion 45. The said sector Si includes an upper surface 63 which is disposed in parallelism with the inner face of the adjacent jaw piece 2S. The actuating lever includes a web portion 6ft which rests upon Jthe live lever and adjacent the end of said web portion there is formed a depending lug 65 which is extended downwardly into the plane of movement of said lever to contact the side edge E6 of the latter. The lug B5 is thus disposed in the path or movement of the live lever and the two levers move in unison during the brake applying movement or" the piston.

The lever 59, beyond the web portion 54, is extended outwardly and upwardly from its pivotal axis towardsA the push rod to present an arm section 6'! lying at an appreciable distance above the live lever. The section El is screw threaded to receive a threaded extension 55 whereby the length of the lever may be varied. The extension 68 is provided at its outer end with an apertured head 69 whereby connection is effected with the compressible mechanism which `forms the motive power for operating the take up device through its actuating lever.

vSaid compressible mechanism includes a guiding and holding rod i0 which is screw threaded at '.'I whereby connection is eected with a clevis member i2 which in turn is pivoted at 73 to the head 69 of the actuating lever structure. The rod 10 at its opposite end is supported by an anchorage bracket I4 which is provided with a slotted aperture 'I5 and beyond said aperture the rod is provided with a rack 'i6 having a series of teeth Tl with which a locking pawl I8 carried by the anchorage bracket 'i4 is adapted to engage as will hereinafter be described. The anchorage bracket 'i4 is preferably mounted on a stationary bracket to which it is connected by a pivot 80. The stationary bracket 19 ispreferablyin the form of a bracket 14 and the clevis 12 and is compressible therebetween. Y y

The operation of the slack adjuster is as follows: assuming the brake in released position as shown in Fig. 1 with'the locking pawl 18 hanging freely in a depending position beyond the rack teeth as shown in Figures 2 and 9, the brake applying operation is eiected by a forward movement of the push rod I5 thereby moving the live lever I1 forwardly and carrying along Athe actuattween the depending lug 615 and the edge 66 of the live lever. The swinging movement of the lever 58 in this manner results in the rotation 0f the bevel gear pinion 46 in an anti-take up direction with the said pinion moving independently of the sleeve 24 on accountof the ratchetting connection between the parts brought about by theV interposition of the axially movable member 4Q. During the forward movement of the push rod the spring 86 is compressed and such compression held by the engagement between paWl 18 and the ratchet teeth 11 thereby causing the live lever to return to released position inde- ,V pendently of the actuating lever 59 until such time as the push rod exceeds the predetermined extent oftravel. y In the-normal operation of the brake the rst of the teeth 11 is arranged to engage at 4% inches of piston travel and successive teeth engaging at 51/2 and 61/2 inches of travel respectively, the latter Y position of Athe parts being indicated in K ing lever 59 by reason of the interengagement bei Fig. 10. Beyond the last tooth which holds the position of the' springV at 61/2 inches of piston travel there is provided a at ledge 81 which holds the pawl 18 in the plane of the locking faces of the teeth and prevents release of the -pawl until such time as the piston travel exceeds the 61/ inches by the distance corresponding to therlength of the ledge 81 which is preferably 1 inch in length to provide for release of the spring at an approximate '1l/2 inches of piston travel.

Upon continued movement of the piston in a brake setting direction beyond the indicated 'I1/2 i inches of travel the pawl 18 overrides'the ledge 81 and moves to release position as indicated in Fig. 11T and the actuating lever is then free to return to release 'position of the brake under the influence of the released spring energy. As the actuating lever 59 returns with the live lever the pinion lll-5 is rotated in a take up direction and the center tie rod structure shortened. During the releasing movement of the spring 86` the upper surface of the ratchet teeth 11 engage the rear of pawl 18 and move the same to inoperative position and upon completion of the release movement the pawl again drops to release as indicated in Fig. 9 in readiness for the next cycle of operations. n

My improved device provides for positive operation and precision of release of the spring energy at the required extent of piston travel and by 6 positioning the compressible mechanism in the linevcorresponding to the path of the push rod travel I obtain a device vin which the operation of the parts may be readily adjusted in relation to piston travel. The use of a bevel gear drive with a large sector for the driving gear and a comparatively small pinion for the driven member is advantageous inasmuch as the limited swinging movement of the actuating lever is translated in a wide sweep of the take up device.

This invention disclosed and claimed herein is an improvement over the invention disclosed in my copending application Serial No. 152,061, led March 27, 1950.

WhatIclaim as new is: I i

1. In a slack adjuster for the airbrake system of a railway vehicle'and the like, in combination with a brake lever and power applying means acting on one end of said lever and a connection pivoted to the lever at an appreciable distance from the brake applying means, said connection having a screw threaded section and a complementary threaded sleeve engaging therewith for varying the length of the connection by rotation of the sleeve; means for automatically effecting rotation of the sleeve upon excessive movement of the brake applying means including a bevel` gear pinion, ratchet means operatively interconnecting said vpinion and said sleeve whereby on rotation ofthe former in one direction the latter is rotated and on rotation of the former in the opposite direction the latter is not rotated, and a cooperating bevel gear member meshing with said pinion and pivotally mounted to swing in a plane substantiallyparallel with the plane of movement of the brake lever; resilient means operatively connected to said bevel gear member and arranged and adapted to oppose'the movement thereof when the same is vmoved in the direction corresponding to the rotation of said pinion in said opposite direction and also operatively connected to the brake applying means so as to be tensioned by movement thereof in a brake setting direction, pawl and ratchet means cooperating with said resilient means to hold the same under tension, and spring energy releasing means controlled by the brake applying means on movement vthereof to azpredetermined position for releasing the `energy stored in said resilient means to rotate the sleeve in a take up direction.

g 2. `In a slack adjuster for vehicle brakes including live and dead levers spaced from each other and power applying means acting on the klive4 gaging the said threaded section, said sleeve hav-` ing an interiorly threaded bore engaging said threaded section `for varying the length of the connection by rotation of the sleeve; means for rotating said sleeve in a screw take up direction upon excessive movement of the power applying means including an actuating lever mounted to swingin a-plane substantially parallel with the plane of movement ofthe live lever and arranged and adaptedto be actuated by movement of the latter upon movement ofY the power applying means in a brake setting direction, a right angular drive operatively interconnecting said actuating lever and said sleeve,` ratchet means interposed in said drive whereby on movement of said .actuating lever in one direction said sleeve is rotated and on movement of said actuating lever in the kopposite 'direction by the power applying means in a brake setting direction said sleeve is not'rotated, resilientmeans Aoperatively connected to said actuating 'lever` and to the power applying means and arranged and adapted to be tensioned upon'movement thereof when setting the brakes, interengaging pawl and ratchet means cooperating with said resilient means to hold the same under tension, and spring energy releasing means controlled by the power applying means on excessive movement thereof for disengaging said pawl andwratchet means to release the energy stored in .said resilient means to move said ac'- tuating lever i'or' rotating said sleeve in a take up direction.

3:, In a slack adjuster .for vehicle brakes including livey and dead levers spaced from each otherandH power,` applyingmeans acting on the live lever; a tieconnection extending between said respective levers and pivotally connected therewith at alccation spaced from .the` power applying means, said tie connection including a screwthreaded section and a sleeve having a screw threaded section cooperating therewith for varying the length. of the connection by rotation of the sleeve in a screwtake up direction upon excessive movement of the brake applying means; the herein described improvement which includes an actuating lever pivotally mounted at a location coincident with the pivotal connection between the live lever and tie rod connection, connecting means between said actuating lever and said live lever whereby the former is movable with the latter in a brake applying direction and is free of the `latter on movement thereof in a brake releasing direction, a right angular drive between said actuating lever and sleeve including ratchetmeans arranged and adapted on movement of said'actuating lever in one direction to rotate. said sleeve and on movement of said actuating lever in the opposite direction by said live lever said sleeve is not'rotated, resilient means arranged and adapted to bias said Vactuating lever in said one direction,'rinterengaging pawl and ratchet means for holding said resilient means 4. In a slack adjuster for. brakes for a car structure including a lever and movable power lapplying means acting on said lever, a tie rod connection pivotally connected to said lever at an appreciable distance from the power applying means, said yconnection having a screw threaded section and a sleeve telescopically engaging the ysaid threaded section, said sleeve having an interiorly threaded bore engaging said threaded section for varying the length of the connection by rotation of the sleeve; means for rotating said sleeve in a screw take up direction upon'excessive movement or" the power applying means including an actuating lever mounted to swing in a plane substantially parallel with the plane of movement of the live lever and movable in a forward direction by means or" the power applying means in setting the brakes, a right angular drive between said actuating lever and sleeve including ratchet means arranged and adapted on movement of said actuating lever in a reverse direction to rotate said sleeve and on movement of said actuating lever in said forward direction not to rotate said sleeve; and a compressible mechanism interposed between said actuating lever and the car structure including an anchoring bracket 8, on the car structure formed with a guide aperture, a rod pivotally mounted on said actuating lever andje'xtending through said guide aperture, a spring encircling said rod and interposed between said actuating lever and said anchoring bracket, ratchet teeth on said rod, and a pawl pivotally mounted on said bracket and engageable with said teeth for holding said spring undertension, said pawl being arranged to move to an inoperative position upon excessive movement oi the power applying means in a brake setting direction to release the energy .stored in said spring for moving said actuating lever in said reverse direction to rotate said sleeve and reduce the length of said connection.

5. In a slack adjuster for brakes for a car structure including a live lever and power applying means acting thereon, a tie rod connection pivotally connected to the lever at an appreciable distance from the power applying means, said tie rod connection including a screw threaded section and a sleeve having a screw threaded section for cooperating therewith whereby the length of the connection is varied by rotation of the sleeve in a take up direction; the herein de-scribed improvement which includes an actuating lever pivotally mounted to swing in a plane substantially parallel with the plane of movement of the live lever and movable in a forward direction by means of the power applying means in setting the brakes, connecting means between said actuating lever and said live lever whereby the former is movable with the latter in a brake applying direction and is iree of the latter on movement thereof in a brake releasing direction, an angle drive between said actuating lever and sleeve including ratchet means arranged and adapted on movement of said actuating lever in a reverse direction to rotate said sleeve and on movement of said actuating lever in said forward direction not to rotate said sleeve; and ccmpressible mechanism eX- ternal to and separate and distinct from said power applying means and interposed between said actuating lever and the car structure for moving the former in said reverse direction independently of said power applying means to rotate said sleeve and reduce the length of said connection.

6. The invention, as set forth in claim 5, whereinA the compressible mechanism includes an anchoring bracket pivotally mounted on the car structure and having guide means therein, a guide rod pivotally mounted cn the actuating lever and extended through said guide means, a spring encircling said guide rod and interposed between the actuating lever and said anchoring bracket, ratchet teeth on said guide rod, and a locking pawl pivotally mounted on said bracket to engage with the respective teeth of said guide rod for holding said spring under tension at various distances of brake travel, said pawl upon excessive movement of the power applying means being arranged to over ride said teeth and re- Y lease the energy stored in said spring.

7. In a slack adjuster for the brakes of a railway car structure and the like including a live lever and movable power applying means acting thereon and a tie rod connection pivotally connected to the live lever at an appreciable dictance from the power applying means, said connection including therein take up mechanism for varying the length of the connection; an actuating lever for the take up mechanism pivotally mounted at a location coincidental with the pivotal axis of theV live lever and the tie rod connection, said lever being extended towards the power applying means; and'resilient compressible mechanism external to and separate and distinct from said power applying means and interposed between said actuating lever and the car structure to bias said actuating lever independently of said power applying means, said resilient mechanism being. compressible on a line extending substantially in alignment with the path of movement of the brake applying means.

8. The structure as set forth in claim 7 wherein the actuating lever is adjustable in length to provide a structure applicable to levers cf different lengths.

9. The structure set forth in claim '7 wherein the actuating lever is carried by the live lever and a depending lug from the actuating levei` is extended to lie in the path of the said live lever whereby the actuating lever is moved by the live lever during the brake applying operation.

10. In a slack adjusterfor the brake of a railway vehicle including a lever and power applying means acting on said lever; a tie connection pivctally connected to said lever at an appreciable distance from the power applying means, said connection being adjustable in length and including a take up connection in the form of a threaded rod section and a complementary' threaded sleeve engaging with said threaded rod section whereby a variation in length of thenconnection is effected by a turning movement of the sleeve, said sleeve having a hub section and integrally formed collars at each end thereof; and a yoke embracing the sleeve and pivotally united with the' said lever, said yoke including a pair of jaw pieces disposedin facing relation on opposite sides of the said leverv and being each formed with a semicircularly shaped end bearing portion adapted to seat in the hub portion of the sleeve and lie between the spaced collars to prevent relative axialmovement between the sleeve and the yoke.

11. The structure set" forth in claim 10 wherein the jaws are providedwith lateral extensions at each side ofthe semicircularly shaped portions and with a forward extension beyond the lever and uniting means at the said lateral and forward extensions.

12. Automatic slack adjusting mechanism for a railway car braking system having brake applying means including live and dead levers connected to the braking system with the live lever connected for energization to a push rod and the levers interconnected by a connecting rod, said slack adjusting mechanism comprising a take up device adaptedto be interposed in said braking system and on operation to vary the relation between the levers and push rod and thereby remove slack from the braking system, an actuating member adapted to be operatively connected to the braking system for movement in a forward direction in response to application of the brakes and operatively connected to said take up device for operating the same to remove slack from the braking system on movement of said actuating member in a reverse direction, spring means cooperating with said actuating member and tensioned thereby on its movement in said forward direction, and restraining means cooperating with said spring means for holding the same under tension on completion of forward movement of said actuating member less than through a predetermined extent and for releasing said spring means to move said actuating member in said reverse direction when the same has been moved through said predetermined extent and the brakes have been released. Y l

13. Automatic slack adjusting mechanism for the braking system of a railway carvstructure having brake applying means including live and dead levers connected to the braking system with the live lever connected for energization to a push rod and the levers interconnected by a connecting rod, said slack adjusting mechanism comprising a take up device adapted to be interposed in said braking system and on operation to vary the relation between the levers and push rod and thereby remove slack from the braking system, an actuating member adapted to be operatively connected to the braking system for movement in a forward direction in response to application of the brakes and operatively connected to said take up device for operating the same to remove slack from the braking system on movement of said actuating member in a reverse direction, spring means adapted to be interposed between the car structure and said actuating member and tensioned thereby on its movement in said forward direction, and restraining means adapted to be carried by said car structure and cooperating with said spring means for holding the same under tension on completion of forward movement of said actuating member less than through a predetermined extent and for releasing said spring means to move said actuating member in said reverse direction when the same has been moved through said predetermined eX- tent and the brakes have been released.

14. Automatic slack adjusting mechanism for a railway car braking system having brake applying means including live and dead levers connected to the braking system with the live lever connected for energization to a push rod and the levers interconnected by a connecting rod, said slack adjusting mechanism comprising a take up device adapted to be interposed in said braking system and on operation to vary the relation between the levers and push rod and thereby, remove slack from the braking system, an actuating member adapted tobe operatively connected to the braking system for movement in a forward direction in response to application of the brakes and operatively connected to said take up device for operating the same to remove slack from the braking system on movement ofv said actuating member in a reverse direction, spring means cooperating with said actuating member and tensioned thereby on its movement in said forward direction, and step by step restraining means cooperating with said spring means for holding the nected to the braking system with the live lever connected for energization to a push rod and the levers interconnected by -a connecting rod, said slack adjusting mechanism comprising a turnbuckle interposed in said connecting rod and on rotation acting to shorten the same to vary the relation between the levers and push rod and thereby remove slack from the braking system, a bell crank having one arm connected to said push rod for movement in a forward direction in response to application of the brakes and another arm connected to said turnbuckle for rotating the same to remove slack from the braking system only on movement of said bell crank in a reverse direction, spring means cooperating with said bell crank and tensioned thereby on its movement in said forward direction, and restraining means cooperating with said spring means for holding the same under tension on completion of forward movement of said bell crank less than through a predetermined extent and for releasing said spring means to move said bell crank in said reverse direction when thesame has been moved through said predetermined eX- tent and after the brakes have been released.

16. Automatic slack adjusting mechanism for a railway car braking system having brake applying means including live and dead levers connected to the braking system with the live lever connected for energization to a push rod and the levers interconnected by a connecting rod, said slack adjusting mechanism comprising a turnbuckle interposed in said connecting rod and on rotation acting to shorten the same to vary the relation between the levers and push rod and thereby remove slack from the braking system, a bell crank having one arm connected to said push rod for movement in a forward direction in response to application of the brakes and an* other arm connected to said turnbuckle for rotating the same to remove slack from the braking system only on movement of said bell crank in a reverse direction, spring means cooperating with said bell crank and tensioned thereby on its movement in said forward direction, and pawl and ratchet means cooperating with said spring means for holding the same under tension on completion of forward movement of said bell crank less than through a predetermined extent and for releasing said spring means to move said bell crank in said reverse direction when the same has been moved through said predetermined extent and after the brakes have been released.

17. Automatic slack adjusting mechanism for the braking system of a railway car structure having brake applying means including live and dead levers connected to the braking system with the live lever connected for energization to a push rod and the levers interconnected by a connecting rod, said slack adjusting mechanism comprising a turnbuckle interposed in said connecting rod and on rotation acting to shorten the same to vary the relation between the levers and push rod and thereby remove slack from the braking system, a bell crank having one arm connected to said push rod for movement in a forward direction in response to application of the brakes and another arm connected to said turnbuckle for rotating the same to remove slack from the braking system only on movement of said bell crank in a reverse direction, spring means interposed between said car structure and said bell crank and tensioned thereby on its movement in said forward direction, and pawl and ratchet means carried by said car structure and cooperating with said spring means for holding the same under tension on completion of forward movement of said bell crank less than through a predetermined extent and for releasing said spring means to move said bell crank in said reverse direction when the same has been moved through said predetermined extent and after the brakes have been released.

GEORGE B. DOREY.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 636,305 Wands NOV. 7, 1899 795,401 Leigh July 25, 1905 1,395,738 Schechter Nov. l, 1921 2,169,137 Bryant Aug. 8, 1939 2,283,966 Brown May 26, 1942 FOREIGN PATENTS Number Country Date 108,401 Switzerland 1925 

